China yesterday (January 7) urged the United States to cancel a massive arms deal to Taiwan, warning of severe consequences if it does not heed the call.

The US defense department announced the contract late on Wednesday, allowing US company Lockheed Martin Corp to sell an unspecified number of Patriot air defense missiles to the island.

The hardware, some of the best in its class, could shoot down the Chinese mainland's short-range and mid-range missiles, Reuters quoted defense analysts as saying.

"This is the last piece that Taiwan has been waiting on," Wendell Minnick, Asia bureau chief of Defense Weekly, said.

The sale rounds out a broad US$6.5-billion arms package approved under former US president George W. Bush in late 2008, he said.

The deal is currently pending notification to the US Congress.

The Foreign Ministry yesterday urged the US "to clearly recognise the severe consequences of arms sales to Taiwan" and protested to Washington, spokeswoman Jiang Yu told a news briefing.

The Ministry of National Defence told China Daily last night it was checking the information with the US.

Jin Canrong, deputy dean of the International Studies School at Renmin University of China, said Beijing is almost certain to retaliate against Washington if the deal is consummated.

"It is likely to freeze military exchanges. It will make the US very uncomfortable because of all the world's strategic military powers, the US is most eager to learn about the PLA."

Rear-Admiral Yang Yi, an expert at the Institute of Strategic Studies of the National Defense University, said it was time for China to sanction the US arms firms behind the deal.

"When it comes to a question of principles, we should never make concessions," he said.

Some US companies which sell weapons to Taiwan also want to sell aircraft and other goods to China, added Yang, without naming any firms.

"Why don't we take defensive countermeasures against them? Apart from just protesting to the US government, why don't we impose sanctions on these troublemakers?"

Sooner or later, Washington will recognise the arms sales "hurt both itself and others" as it will suffer from strained relations with China, Yang said.

He also rebuffed claims that the arms sales will not stop as they are stipulated in US law. "There is nothing in the world that can never be changed We should make continuous efforts to reshape the policy choices of the US".

However, Niu Jun, a professor on US studies at Peking University, questioned the feasibility of sanctions as the US will, in turn, penalise Chinese companies.

But Chinese netizens have spontaneously called for a boycott of US companies behind the arms deal.

They launched a massive boycott of French retail chain Carrefour and luxury brand Louis Vuitton after the Beijing Olympics torch relay was interrupted in Paris in 2008. Since then, Internet users have become a powerful factor holding sway in diplomacy.

In a public letter last month targeting United Technologies, producer of the UH-60 Black Hawk helicopters supplied to Taiwan, a Chinese netizen named Dai Jianfen called for the boycott of all the firm's products and deals. United Technologies is reported to be one of the largest foreign investors on the Chinese mainland.

A survey by a major Chinese website showed nearly 96 per cent of the voters were supportive of such a boycott.

Business relations between Lockheed Martin and the Chinese mainland are unclear.

Wu Nengyuan, director of the Institute of Taiwan Studies at the Fujian Academy of Social Sciences, said the arms sale is casting a shadow over improving relations across the Taiwan Straits.

"To eradicate the problem, the Chinese mainland and Taiwan should reach a peace agreement," he said.With reports from agencies